In
signal processing, noise is a general term for unwanted (and, in general, unknown) modifications that a
signal may suffer during capture, storage, transmission, processing, or conversion.[1]
Sometimes the word is also used to mean signals that are
random (
unpredictable) and carry no useful
information; even if they are not interfering with other signals or may have been introduced intentionally, as in
comfort noise.
Noise reduction, the recovery of the original signal from the noise-corrupted one, is a very common goal in the design of signal processing systems, especially
filters. The mathematical limits for noise removal are set by
information theory.
Types of noise
Signal processing noise can be classified by its statistical properties (sometimes called the "
color" of the noise) and by how it modifies the intended signal:
A long list of noise measures have been defined to measure noise in signal processing: in absolute terms, relative to some standard noise level, or relative to the desired signal level. They include:
Dynamic range, often defined by inherent noise level